Exporters are packages (similar to an npm package, for example) that transform design system data into production code. Each exporter package is unique to which platform, technology or stack it targets, and in the code it produces.
The Exporters section of Supernova (found in Code automation) contains exporters provide out-of-the-box code generation solutions.
When building your own exporters, they will be private by default, and you can later choose to publish the exporter to the marketplace if you feel it would be useful to other developers.
You can learn more about using exporters, and building your own, in our Developer documentation.